1. Field of the Disclosure
The present disclosure relates generally to a wireless communication system and, more particularly, to a method and an apparatus for detecting transmission power in a wireless communication system.
2. Description of the Related Art
A power detector detects output power of a Radio Frequency (RF) transceiver in a wireless communication system.
The power detector may include multiple gain amplifiers and multiple current conversion circuits, with an input voltage of the power detector amplified by the multiple gain amplifiers, and the amplified input voltage converted into a current by each of the multiple current conversion circuits. The sum of the currents, which are output from the multiple current conversion circuits, appears at an output terminal of the power detector, with an output voltage of the power detector obtained across an output resistor (Rout).
When each of the multiple gain amplifiers operates in a saturation state, the output voltage of the power detector may linearly increase. The output voltage of the power detector has a transfer function, having an ideal linear response and a predetermined slope in response to input power, in a desired input power range. The power detector may need a wide dynamic range, wider than or equal to 40 dB, in order to detect an entire transmission output power range.
As described above, power detectors determine an output voltage by combining currents from each of multiple current conversion circuits. However, all of the multiple gain amplifiers and all of the multiple current conversion circuits must simultaneously operate, resulting in significant power consumption.
Also, power detectors often have difficulty outputting a pure linear response since the gain amplifiers and the current conversion circuits are not ideal elements. The non-linear characteristics of these non-ideal elements cause a curved output of the power detectors. Further, input power has a variable peak component which affects a dynamic range of a gain amplifier, causing an error at an input power transition point.
Therefore, additional calibration is needed to maintain linearity of the output voltage of power detectors.